Definition.—Phractopeltida with twenty simple radial spines, bearing no free apophyses outside the outer shell.
The genus Phractopelta is the most simple form among the Phractopeltida, and may be regarded as the common ancestral form of this family. All twenty spines are of nearly equal form and size, and bear no free apophyses on their free part, outside the two concentric shells. Phractopelta may be derived from Orophaspis by further development of the free apophyses, which by union of their branches form a second outer shell around the primary shell of that Dorataspid.
Definition.—Outer shell composed of twenty separated plates, the sutures of their meeting condyles not being grown together.
1. Phractopelta dorataspis, n. sp. (Pl. 133, fig. 1).
Outer shell composed of twenty plates, the meeting condyles of which are separated by permanent sutures. Each plate commonly with two elliptical aspinal pores, which are two to three times as broad as the irregular sutural pores. Radial spines (in the outer free part) compressed, linear, twice as long as the diameter of the shell.
Dimensions.—Diameter of the outer shell 0.11, of the inner 0.05.
Habitat.—North Pacific (off Japan), Station 239, surface.
2. Phractopelta dyadopora, n. sp.
Outer shell composed of twenty plates, the meeting condyles of which are separated by permanent sutures. Each plate commonly with two kidney-shaped aspinal pores, which are three to four times as broad as the irregular sutural pores. Radial spines conical, about as long as the radius of the shell.
Dimensions.—Diameter of the outer shell 0.08, of the inner 0.04.
Habitat.—North Pacific, Station 256, surface.
3. Phractopelta diporaspis, n. sp.
Outer shell composed of twenty plates, the meeting condyles of which are separated by permanent sutures. Each plate commonly with two quadrangular aspinal pores, which are four to five times as broad as the irregular sutural pores. Radial spines compressed, sword-shaped, about as long as the diameter of the shell.
Dimensions.—Diameter of the outer shell 0.09, of the inner 0.04.
Habitat.—South Atlantic, Station 332, surface.
4. Phractopelta tessaraspis, n. sp.
Outer shell composed of twenty plates, the meeting condyles of which are separated by permanent sutures. Each plate commonly with four crossed, quadrangular, aspinal pores, the two opposite of which are much larger than the two others. Sutural pores small, roundish. Radial spines compressed, linear, about twice as long as the diameter of the shell.
Dimensions.—Diameter of the outer shell 0.084, of the inner 0.032.
Habitat.—North Pacific (off Japan), Station 238, surface.
5. Phractopelta tetradopora, n. sp.
Outer shell composed of twenty plates, the meeting condyles of which are separated by permanent sutures. Each plate commonly with four crossed quadrangular (or nearly circular) aspinal pores, all of nearly the same size. Sutural pores polygonal or roundish. Radial spines cylindrical, two to three times as long as the diameter of the shell.
Dimensions.—Diameter of the outer shell 0.11, of the inner 0.045.
Habitat.—North Pacific, Station 253, surface.
6. Phractopelta hexadopora, n. sp.
Outer shell composed of twenty plates, the meeting condyles of which are separated by permanent sutures. Each plate commonly with six aspinal pores, the two opposite of which are much larger than the four others. Sutural pores small, roundish. Radial spines compressed, two-edged, larger than the diameter of the shell.
Dimensions.—Diameter of the outer shell 0.1, of the inner 0.04.
Habitat.—Central Pacific, Station 272, surface.
7. Phractopelta octadopora, n. sp.
Outer shell composed of twenty plates, the meeting condyles of which are separated by permanent sutures. Each plate commonly with eight aspinal pores, the four crossed being larger than the four others alternating with them. Sutural pores irregular. Radial spines conical, shorter than the diameter of the shell.
Dimensions.—Diameter of the outer shell 0.12, of the inner 0.04.
Habitat.—Indian Ocean (Cocos Islands, surface), Rabbe.
Definition.—Outer shell composed of twenty united plates, the sutures of their meeting condyles being grown together.
8. Phractopelta aspidomma, n. sp.
Outer shell composed of twenty united plates, the meeting condyles of which are grown together. On the base of each radial spine (where its outer free part arises from the surface of the outer shell), two large elliptical aspinal pores, two to four times as large as the other roundish pores. Radial spines compressed, sword-shaped, about as long as the radius of the shell.
Dimensions.—Diameter of the outer shell 0.1, of the inner 0.05.
Habitat.—Equatorial Atlantic, Station 347, surface.
9. Phractopelta haliomma, n. sp.
Outer shell composed of twenty united plates, the meeting condyles of which are grown together. On the base of each radial spine two large kidney-shaped aspinal pores, little larger than the other irregular pores. Radial spines compressed, linear, two-edged, much longer than the diameter of the shell.
Dimensions.—Diameter of the outer shell 0.09, of the inner 0.03.
Habitat.—South Pacific, Station 295, surface.
10. Phractopelta tessaromma, Haeckel.
Outer shell composed of twenty united plates, the meeting condyles of which are grown together. On the base of each radial spine four crossed egg-shaped aspinal pores, two opposite of which are much larger than the two others. Sutural pores irregular. Radial spines cylindrical or little compressed, thin, longer than the diameter of the shell.
Dimensions.—Diameter of the outer shell 0.1, of the inner 0.04.
Habitat.—Central Pacific, Station 266, surface.
11. Phractopelta hystrix, Haeckel.
Haliomma hystrix, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 37, Taf. v. figs. 1, 2.
Aspidomma hystrix, Haeckel, 1862, Monogr. d. Radiol., p. 424.
Outer shell composed of twenty united plates, the meeting condyles of which are grown together. On the base of each radial spine four crossed circular aspinal spines of equal size. Sutural pores roundish, of about the same size. Radial spines conical, about as long as the radius of the shell.
Dimensions.—Diameter of the outer shell 0.07, of the inner 0.024.
Habitat.—Mediterranean (Nice), J. Müller, surface.
Definition.—Phractopeltida with twenty radial spines, each of which is protected by two free external apophyses.
The genus Pantopelta differs from all other Phractopeltida in the development of free protecting apophyses on all twenty radial spines. Only a single specimen of this rare form was seen, and in this all twenty spines exhibited no marked differences in form and size, but were more or less irregularly developed.
1. Pantopelta icosaspis, n. sp. (Pl. 133, fig. 4).
Apophyses of all twenty radial spines with forked anastomosing branches, forming a more or less irregular cup-like fenestrated shield, pierced by a variable number of pores. Distance of the apophyses from the outer shell equal to half its radius. Pores of the outer shell irregular, roundish, four to six times as broad as those of the inner shell. Radial spines compressed, sword-shaped, longer than the radius of the shell.
Dimensions.—Diameter of the outer shell 0.08, of the inner 0.03.
Habitat.—Antarctic Ocean, Station 157, depth 1950 fathoms.
Definition.—Phractopeltida with twelve simple spines (four equatorial and eight polar), and with eight tropical spines protected by external free apophyses.
The genus Octopelta differs from the other Phractopeltida in the possession of eight shields or pairs of free apophyses outside the outer lattice-shell; the spines bearing these apophyses are the eight tropical spines. The twelve other spines (eight polar and four equatorial) are quite simple, without apophyses.
1. Octopelta cultella, n. sp.
Apophyses of the eight tropical spines simple, compressed, knife-shaped, about as long as their distance from the outer shell. On the base of each spine (in the network of the outer shell) two orthogonal aspinal pores, two to three times as long as the other polygonal pores.
Dimensions.—Diameter of the outer shell 0.08, of the inner 0.03.
Habitat.—Tropical Atlantic, Station 338, surface.
2. Octopelta furcella, n. sp.
Apophyses of the eight tropical spines forked, each with two parallel simple fork-branches, about as long as their distance from the outer shell. On the base of each spine (in the outer shell) two kidney-shaped aspinal pores, about twice as broad as the other irregular pores.
Dimensions.—Diameter of the outer shell 0.1, of the inner 0.04.
Habitat.—South Atlantic (off Tristan d'Acunha), Station 332, surface.
3. Octopelta scutella, n. sp. (Pl. 133, fig. 5).
Apophyses of the eight tropical spines crossed by a transverse beam, which is again crossed by two perpendicular branches; by union of these branches each tropical spine forms a square shield with four crossed pores and twelve to sixteen marginal spikes. On the base of each spine (in the surface of the outer shell) four crossed aspinal pores which correspond to those of the free shields; these are somewhat larger than the other pores.
Dimensions.—Diameter of the outer shell 0.12, of the inner 0.06.
Habitat.—Tropical Atlantic, Station 348, surface.
Definition.—Phractopeltida with eight simple spines (four equatorial and four hydrotomical polar spines) and with twelve spines protected by external free apophyses (eight tropical and four geotomical polar spines).
The genus Dorypelta, the most common of all Phractopeltida which are protected by free apophyses, exhibits a very peculiar differentiation of its twenty radial spines. There are constantly eight simple spines and twelve spines with apophyses. The eight simple spines are the four equatorial spines and four polar spines placed in the hydrotomical median plane. The four other polar spines (placed in the geotomical meridian plane) and the eight tropical spines are protected by two opposite apophyses, which are now simple, now branched or shield-shaped. A similar differentiation occurs in no other Acanthophractida.
Definition.—Free apophyses of the radial spines simple, not branched.
1. Dorypelta stauroptera, n. sp.
Apophyses of the long compressed radial spines simple, conical, about as long as their distance from the shell. At the base of each spine (in the outer shell) two elliptical aspinal pores, two to three times as large as the other pores.
Dimensions.—Diameter of the outer shell 0.1, of the inner 0.044.
Habitat.—North Pacific, Station 238, surface.
2. Dorypelta gladiata, n. sp.
Apophyses of the long cylindrical radial spines simple, triangular, about half as long as their distance from the shell. At the base of each spine (in the outer shell) four crossed aspinal pores, the two opposite of which are much larger than the other two pores.
Dimensions.—Diameter of the outer shell 0.09, of the inner 0.04.
Habitat.—Central Pacific, Station 266, surface.
Definition.—Free apophyses of the radial spines branched, with free (not anastomosing) branches.
3. Dorypelta furcata, n. sp.
Apophyses of the long compressed spines simply forked, each with two simple parallel fork-branches. At the base of each spine two elliptical aspinal pores, much larger than the other roundish pores.
Dimensions.—Diameter of the outer shell 0.08, of the inner 0.04.
Habitat.—Central Pacific, Station 274, surface.
4. Dorypelta tetrodon, n. sp.
Apophyses of the long compressed spines crossed by a transverse beam, which bears four simple parallel fork-branches or spikes (perpendicular to the beam), two larger medial and two smaller lateral. At the base of each spine four crossed aspinal pores of nearly equal size, little different from the other pores.
Dimensions.—Diameter of the outer shell 0.09, of the inner 0.035.
Habitat.—South Pacific, Station 284, surface.
5. Dorypelta ramosa, n. sp.
Apophyses of the long cylindrical spines crossed by a transverse beam, which bears four to six irregularly branched spikes or fork-branches, the medial of which are larger than the lateral. At the base of each spine four crossed aspinal pores, two opposite of which are much larger than the two other pores.
Dimensions.—Diameter of the outer shell 0.09, of the inner 0.04.
Habitat.—South Pacific, Station 302, surface.
Definition.—Free apophyses of the radial spines branched, and forming perforated shields by union of their anastomosing branches.
6. Dorypelta lithoptera, n. sp.
Apophyses of the long compressed radial spines with anastomosing branches; each spine bearing two free separated shields (each with two roundish aspinal pores). At the base of each spine (in the network of the outer shell) two elliptical aspinal pores, larger than the other pores.
Dimensions.—Diameter of the outer shell 0.09, of the inner 0.03.
Habitat.—North Pacific, Station 239, surface.
7. Dorypelta tessaraspis, n. sp. (Pl. 133, fig. 2).
Apophyses of the long cylindrical spines with anastomosing branches; each spine bearing a single free shield with four crossed aspinal pores of equal size (on the margin of the shield twelve to sixteen spikes). At the base of each spine (in the outer shell) four crossed aspinal pores, about as large as the other roundish pores.
Dimensions.—Diameter of the outer shell 0.11, of the inner 0.05.
Habitat.—Central Pacific, Station 263, surface.
8. Dorypelta dodecaspis, n. sp.
Apophyses of the long two-edged spines with anastomosing branches; each spine bearing a single free shield with six to eight parmal pores (four crossed aspinal pores alternating with four outer coronal pores), on the margin of each shield twelve to sixteen spikes. At the base of each spine (in the outer shell) four crossed aspinal pores, about as large as the other irregular pores.
Dimensions.—Diameter of the outer shell 0.1, of the inner 0.04.
Habitat.—North Pacific (off Japan), Station 235, surface.
Definition.—Phractopeltida with four simple equatorial spines and sixteen spines protected by external free apophyses (eight tropical and eight polar spines).
The genus Stauropelta is distinguished from the other Phractopeltida by the possession of sixteen pairs of free apophyses (on the eight tropical and the eight polar spines); only the other four equatorial spines remain simple, without apophyses, and form a simple cross in the equatorial plane.
1. Stauropelta cruciata, n. sp. (Pl. 133, fig. 3).
Apophyses of the long polar and tropical spines crossed by a transverse beam, which is again crossed by two perpendicular branches parallel to the apophyses; branches with free ends, not united by concrescence. At the base of each spine (in the outer shell) two large elliptical aspinal pores, larger than the other irregular pores. Four equatorial spines simple, without apophyses, of the same size as the other sixteen spines.
Dimensions.—Diameter of the outer shell 0.12, of the inner 0.05.
Habitat.—Indian Ocean (Madagascar), Rabbe, surface.
2. Stauropelta stauropora, n. sp.
Apophyses of the long polar and tropical spines crossed by a transverse beam, which is again crossed by two perpendicular branches parallel to the apophyses; these branches are united by concrescence, and form a square shield with four crossed pores, the centre of which is pierced by the spine. At the base of each spine (in the outer shell) four crossed aspinal pores, corresponding to those of the shield, of about the same size as the other roundish pores. Four equatorial spines, simple, without apophyses, somewhat larger than the other sixteen spines.
Dimensions.—Diameter of the outer shell 0.1, of the inner 0.04.
Habitat.—Indian Ocean, Sunda-Archipelago, Singapore, Trebing, surface.
Definition.—Shell ellipsoidal, lenticular or diploconical, with radial beams of different size.
Definition.—Acantharia with a simple ellipsoidal lattice-shell, composed of the branched apophyses of twenty radial spines meeting in its centre and disposed according to the Müllerian law of Icosacantha. Two opposite equatorial spines larger than the two others. Central capsule ellipsoidal, enclosed in the fenestrated shell.
The family Belonaspida, formerly united by me with the Dorataspida (in the Prodromus, 1881, p. 468), differs from it in the ellipsoidal form of the lattice-shell and the enclosed central capsule. In the spherical Dorataspida, their ancestral family, all twenty radial spines are of equal size, whilst here in the Belonaspida two opposite spines are larger than the eighteen others. These two larger or principal spines are both equatorial spines, placed in the longitudinal or major axis of the ellipsoid, or the "hydrotomical axis" (compare above, p. 719). The two other equatorial spines are constantly smaller, and lie in the transverse or minor axis of the ellipsoid, or the "geotomical axis." The geometrical proportion of these two determining axes of the ellipsoidal shell is very variable (even in one and the same species), commonly 4 : 3 or 3 : 2, rarely 2 : 1, often only 5 : 4 or 6 : 5. All meridian planes, passing through the principal spines (or the longitudinal axis of the shell) are elliptical, and of equal size. All transverse planes, perpendicular to that axis, are circular; the largest of these circular parallel planes is the geotomical plane, which passes through the smaller equatorial spines and the spineless axis.
In the spherical Dorataspida the internal length of the radial spines (or the distance between the shell and the centre) is equal in all twenty spines. In the ellipsoidal Belonaspida this internal length is different, and commonly exhibits four different degrees; in the two principal spines it is of first rank, in the eight tropical spines of second rank, in the four (hydrotomical) polar spines of third rank, and in the six spines (four geotomical polar spines and two transverse equatorial spines) of fourth rank. These differences of the internal length become more important the more the hydrotomical axis is prolonged. Regarding all other qualities (in form, disposition, and mode of junction at the centre) the ellipsoidal Belonaspida do not differ from their ancestral group, the spherical Dorataspida (compare above, p. 802). In both families the pyramidal central bases of the twenty spines are commonly supported one upon another with their triangular neighbouring faces; but sometimes also here (particularly in Phatnaspis) the central bases are perfectly grown together. In this case also the sutures of the meeting branches of the apophyses are obliterated, whilst usually they remain open. Such forms, with spines and plates perfectly grown together, form a single piece of acanthin, and were formerly separated by me as a peculiar genus Haliommatidium (Monogr. d. Radiol., 1862, p. 419). But as I now find this concrescence to be an accidental and inconstant peculiarity of some species, it no longer seems to me to be of generic importance.
The apophyses of the twenty radial spines, the branches of which compose the ellipsoidal lattice-shell, exhibit in all Belonaspida the same appearance as in the Diporaspida (and especially the Ceriaspida) among the spherical Dorataspida. Everywhere each radial spine gives off only two opposite primary apophyses, the fork-branches of which unite together and form a plate or shield with two aspinal pores (as in Dorataspis). Commonly the shell exhibits only these forty parmal pores, the other meshes between them being sutural pores. Only in one genus, Phatnaspis (Pl. 136, figs. 6-9), is this number multiplied; the two opposite primary apophyses are here crossed by numerous perpendicular lateral branches, and these are again united by secondary perpendicular ramules which are parallel to the apophyses themselves; therefore each plate here forms a rhombic shield pierced by very numerous (often more than one hundred) small quadrangular or circular pores. Only two of these numerous parmal pores are the primary aspinal pores (sometimes, as in Pl. 136, fig. 8, distinguished by their larger size); all others are secondary or coronal pores. Therefore Phatnaspis repeats the characteristic formation of Coscinaspis, from which it differs in its ellipsoidal shell.
Moreover, the four other genera of the ellipsoidal Belonaspida correspond perfectly to certain genera of the spherical Dorataspida, and may be derived from these by hypertrophy or stronger development of two opposite equatorial spines. In Thoracaspis and Belonaspis (Pl. 139, figs. 8, 9) the surface of the shell-plates is without crests and dimples (in the former without, in the latter with accessory by-spines); they thus correspond to Dorataspis and Diporaspis among the Dorataspida. In two other genera the surface of the shell-plates bears a network of elevated crests, separating funnel-shaped dimples, in Dictyaspis without, in Coleaspis with by-spines; these correspond to Ceriaspis and Hystrichaspis among the Dorataspida. The small by-spines, covering the surface, exhibit the same forms as in the Dorataspida; but they are usually smaller, and less developed in the Belonaspida.
The twenty radial spines are commonly more or less compressed or two-edged, sometimes very flat, broad, and triangular (Pl. 139, figs. 8, 9). In some species (mainly of Phatnaspis) they are very long, thin, and needle-shaped (Monogr. d. Radiol., 1862, Taf. xxii. figs. 10-12). Rarely they are cylindrical, four-edged, or prismatic. The Belonaspida testify by this and other peculiarities to their near relation to the Diporaspida and Phractacanthida and their older origin from Zygacantha.
The Central Capsule is in the Belonaspida ellipsoidal, and more or less prolonged in the hydrotomical or longitudinal axis of the shell. It is constantly smaller than the enveloping ellipsoidal shell, and separated from it by the calymma. Its structure and the shape of its nucleus are the same as in the nearly allied Dorataspida.
|
II. Subfamily Coleaspida. Forty parmal pores (two aspinal pores on each plate, no coronal pores). |
brace | Plates not dimpled, without prominent crests. | brace | No by-spines, | 371. Thoracaspis. |
| With by-spines, | 372. Belonaspis. | ||||
| Plates dimpled, with a network of prominent crests, | brace | No by-spines, | 373. Dictyaspis. | ||
| With by-spines, | 374. Coleaspis. | ||||
|
II. Subfamily Phatnaspida. Eighty to two thousand or more parmal pores (two aspinal pores on each plate, surrounded by two to one hundred or more coronal pores). |
brace | No by-spines (plates not dimpled), | 375. Phatnaspis. | ||
| I. Subfamily Coleaspida. Forty parmal pores (two aspinal pores on each plate, no coronal pores). | ||||||
| Plates not dimpled, without prominent crests. | ||||||
| No by-spines, | ||||||
| 371. Thoracaspis. | ||||||
| With by-spines, | ||||||
| 372. Belonaspis. | ||||||
| Plates dimpled, with a network of prominent crests, | ||||||
| No by-spines, | ||||||
| 373. Dictyaspis. | ||||||
| With by-spines, | ||||||
| 374. Coleaspis. | ||||||
| II. Subfamily Phatnaspida. Eighty to two thousand or more parmal pores (two aspinal pores on each plate, surrounded by two to one hundred or more coronal pores). | ||||||
| No by-spines (plates not dimpled), | ||||||
| 375. Phatnaspis. | ||||||
Definition.—Belonaspida with forty parmal pores (two on each plate), without dimples and crests, also without by-spines, therefore with smooth surface.
The genus Thoracaspis is the simplest form among the Belonaspida, and repeats in this family the nearly allied genus Dorataspis among the Dorataspida. It differs from this genus only in the characteristic prolongation of one equatorial axis, which effects an ellipsoidal transformation of the spherical central capsule and the enclosing lattice-shell.
1. Thoracaspis ellipsoides, n. sp.
Parmal pores large, elliptical, five or six times as large as the small circular sutural pores. Each plate surrounded by five or six sutural pores (a single one on each side). Spines compressed triangular, sword-like, two-edged; inner and outer half of nearly equal length.
Dimensions.—Length of the ellipsoidal shell (or major axis) 0.15, breadth (or minor axis) 0.12; length of the spines 0.07, basal breadth 0.016.
Habitat.—North Pacific, Station 253, surface.
2. Thoracaspis nephropora, n. sp.
Parmal pores large, kidney-shaped, three to four times as large as the roundish small sutural pores. Each plate surrounded by five or six sutural pores (a single one on each side). Spines in the inner longer part cylindrical, in the outer shorter part conical, not compressed.
Dimensions.—Length of the shell 0.2, breadth 0.15; length of the spines 0.06, basal breadth 0.018.
Habitat.—Central Pacific, Station 268, surface.
3. Thoracaspis circopora, n. sp.
Parmal pores circular, of the same size as the circular sutural pores. Each plate surrounded by five or six sutural pores (a single one on each side). Spines compressed, thin, linear, two-edged; outer part one and a half times as long as the inner.
Dimensions.—Length of the shell 0.17, breadth 0.13; length of the spines 0.12, basal breadth 0.003.
Habitat.—South Pacific, Station 288, surface.
4. Thoracaspis bipennis, n. sp. (Pl. 139, fig. 8).
Parmal pores elliptical, about twice as large as the circular sutural pores, which are of rather variable size. Each plate surrounded by eight to twelve sutural pores (commonly two on each side). Spines compressed, triangular, gradually tapering towards both ends; outer half a little longer, and much broader than the inner.
Dimensions.—Length of the shell 0.14, breadth 0.12; length of the spines 0.08, basal breadth 0.025.
Habitat.—Central Pacific, Station 274, surface.
Definition.—Belonaspida with forty parmal pores (two on each plate), without dimples and crests, but with numerous by-spines on the surface.
The genus Belonaspis differs from its ancestral genus Thoracaspis only in the possession of numerous superficial by-spines, and bears therefore to it the same relation as Diporaspis does to Dorataspis. The two latter differ from the two former in the spherical form of the central capsule and the enclosing shell, which here becomes ellipsoidal.
1. Belonaspis pandanus, n. sp.
Parmal pores elliptical, three or four times as large as the circular sutural pores. Each plate surrounded by five or six sutural pores (a single one on each side). Spines compressed, triangular; outer part half as long as the inner, and twice as long as the numerous, simple, bristle-shaped by-spines.
Dimensions.—Length of the ellipsoidal shell (or major axis) 0.12, breadth (or minor axis) 0.1; length of the spines 0.03, basal breadth 0.02.
Habitat.—South Pacific, Station 295, surface.
2. Belonaspis furcata, n. sp.
Parmal pores elliptical, twice as broad as the circular sutural pores. Each plate surrounded by five or six sutural pores (a single one on each side). Spines compressed, linear, very thin; outer part longer than the inner. By-spines very numerous, half as long as the radius, furcate, with divergent fork-branches.
Dimensions.—Length of the shell 0.1, breadth 0.08; length of the spines 0.12, breadth 0.003.
Habitat.—Indian Ocean (Cocos Islands), Rabbe, surface.
3. Belonaspis datura, n. sp. (Pl. 139, fig. 9).
Parmal pores elliptical, three or four times as large as the circular sutural pores. Each plate surrounded by ten or twelve sutural pores (two on each side). Spines triangular, two-edged, about as long as the radius of the shell; gradually tapering from its surface towards both ends. By-spines very short and numerous, simple.
Dimensions.—Length of the shell 0.13, breadth 0.11; length of the spines 0.08, basal breadth 0.025.
Habitat.—Central Pacific, Station 271, surface.
4. Belonaspis lanceolata, n. sp.
Parmal pores elliptical, six or eight times as large as the small circular sutural pores. Each plate surrounded by ten to twelve sutural pores (two on each side). Spines lanceolate, flat, in the distal part needle-shaped, about as long as the diameter of the shell. By-spines very numerous, zigzag, half as long as the shell-radius.
Dimensions.—Length of the shell 0.15 breadth 0.13; length of the spines 0.14, basal breadth 0.03; length of the by-spines 0.04.
Habitat.—North Pacific, Station 235, surface.
5. Belonaspis conifera, n. sp.
Parmal pores kidney-shaped, three or four times as large as the small circular pores. Each plate surrounded by ten to twelve sutural pores (two on each side). Spines very thick, half as long in the outer conical part as in the inner cylindrical part. By-spines very short, conical.
Dimensions.—Length of the shell 0.2, breadth 0.16; length of the spines 0.05, basal breadth 0.03.
Habitat.—Central Pacific, Station 267, surface.
6. Belonaspis multiforis, n. sp.
Parmal pores circular, of the same size as the circular sutural pores. Each plate surrounded by fifteen to eighteen sutural pores (three on each side). Spines compressed, about as long as the radius. By-spines very numerous, zigzag, half as long as the radius.
Dimensions.—Length of the shell 0.22, breadth 0.18; length of the spines 0.12, basal breadth 0.012; length of the by-spines 0.06.
Habitat.—Equatorial Atlantic, Station 347, surface.
Definition.—Belonaspida with forty parmal pores (two on each plate), without by-spines, but with a network of prominent crests on the dimply surface.
The genus Dictyaspis repeats among the Belonaspida the characteristic structure of Ceriaspis (among the Dorataspida), by the development of prominent crests forming a network with dimples on the outer surface of the shields. Either all the dimples or only a part of them are pierced by a pore. The forty aspinal pores are united in pairs in twenty larger dimples. The shell is usually very thick-walled and non-transparent.
1. Dictyaspis solidissima, Haeckel.
Dorataspis solidissima, Haeckel, 1862, Monogr. d. Radiol., p. 416, Taf. xxii. figs. 6-9.
Surface of the shell with seventy to eighty funnel-shaped dimples, each of which is perforated at the base by one or two small meshes; twenty larger dimples in the centre of the plates (each with two elliptical aspinal pores), and fifty to sixty smaller sutural dimples between them (each with a single circular pore). All pores of nearly the same size. No blind dimples. Outer conical part of the thick radial spines of the same length as the inner cylindrical part. Radius of the shell four times as large as the thickness of its wall.
Dimensions.—Length of the shell 0.12, breadth 0.1; length of the spines 0.06, basal breadth 0.012.
Habitat.—Mediterranean (Messina), surface.
2. Dictyaspis favosa, n. sp.
Surface of the shell with one hundred and seventy to one hundred and ninety deep funnel-shaped dimples, seventy to eighty of which are perforated, the others blind; among the former each of the fifty to sixty smaller contains a single sutural pore, each of the twenty larger a couple of aspinal pores. All pores of nearly the same size. Outer part of the compressed two-edged spines triangular, half as long as the inner part. Radius of the shell six times as large as the thickness of its wall. (Differs from Ceriaspis favosa, Pl. 138, fig. 6, mainly in the ellipsoidal form of the shell and the different size and form of the spines.)
Dimensions.—Length of the shell 0.16, breadth 0.13; length of the spines 0.04, basal breadth 0.025.
Habitat.—Central Pacific, Station 265, surface.
3. Dictyaspis compacta, n. sp.
Surface of the shell with one hundred and seventy to one hundred and ninety deep funnel-shaped dimples, seventy to eighty of which are perforated, the others blind; among the former each of fifty to sixty each contain a single sutural pore, twenty each a couple of aspinal pores. All dimples nearly of the same size, very deep. Outer part of the compressed sword-like spines somewhat longer than the inner part. Radius of the dark shell only twice as large as the thickness of its compact wall.
Dimensions.—Length of the shell 0.18, breadth 0.15; length of the spines 0.12, basal breadth 0.02.
Habitat.—Central Pacific, Station 274, surface.